Funds are requested to support the travel of scientists to the eleventh bi-annual Gordon Research Conference on Mutagenesis, to be held at Plymouth State College, Plymouth, New Hampshire, from June 21 through June 26, 1998. The selected speakers are experts in the field of mutagenesis and the conference will provide the opportunity to discuss their latest results and ideas. Of equal importance, the meeting will serve as a forum for extensive interactions among all attending scientists through the Discussion Sessions and Poster Presentations. Selected poster presenters (generally students and younger scientists) will be given the opportunity to introduce their research results for discussion in short presentations (five minutes with overheads). The conference is typically oversubscribed with attendance being limited to 135 persons. The participants are selected from universities, government research laboratories, regulatory agencies, research institutes, and industrial laboratories worldwide. The 1998 Conference will extend understanding of the mechanisms by which mutations occur and the strategies employed by organisms to modulate mutagenesis. In brief, the nine sessions will include two on the role of DNA polymerases and their editing activities in controlling replication fidelity, the role of mismatch repair in modulating potentially mutagenic lesions, two on the processing of endogenous DNA damage, one on homologous recombination mechanisms, one on non-homologous recombination and double strand break repair, one on the inter-relationships among DNA transactions and their potential role in genomic instability, and a special session that focuses on delineation of at-risk sequences in the human genome. In summary, the conference will examine mutagenesis from biochemical, molecular and genetic viewpoints. The field of mutagenesis is important to the discussion of human health since mutations, induced spontaneously or from exogenous sources, appear to initiate or facilitate the progression of a multitude of human diseases, particularly cancer.